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Room Temp/Humidity Control Sequence

Does anyone have and is willing to share some logic or a sequence that basically incorporates humidity in a zone and adjusts the room set point depending on the humidity? Basically I have this reoccurring problem where a user constantly adjusts the room set point because of comfort and the issue is not temperature but the changing humidity levels.

The control line is Alerton and the units are fan coils with modulating chilled water, hot water, economizer. I was speaking more generally about this issue since I see this problem with many jobs in the past.

The chilled coil is after the heating coil. Im not really looking for a dehumidification sequence, what I am looking for is a control algorithm that adjust zone temp set point when the space humidity increases or decreases, to anticipate comfort levels.

I would have thought that Alerton have some sort of 'Reset' block or code.
i.e. when input is at level 'a' then output = x
when input is at level 'b' then output = y
any input between a or b = a proportional output value of x to y

Last edited by Keith D; 06-19-2014 at 07:08 PM.
Reason: im just old and confused

It could be that your system is just not sized properly. The discharge from the unit to maintain space temperature may not be cold enough to provide adequate dehumidification. It sounds like you are trying to fix a mechanical design issue with controls.

The new Honeywell thermostat Lyric supposedly has some feature that it will self-adjust the temperature based on the relative humidity. I guess they did some research and found that most temperature adjustments made by occupants are driven by comfort levels associated with increases or decreases of humidity. I do this at my house all the time. I am trying to see if anyone has translated this strategy to the DDC world.

Fisha,
Sizing of Systems are critical so that the Cooling is On for longer periods of time, which will remove the humidity from the air as condensate.

Changing Setpoints of the Room Temp up and down are not the solution, because that method will always make the Space uncomfortable before it becomes comfortable, as your Room Temp will swing outside of the allowable max of a 2.0 F range. The reason the System works to dehumidify, is basically because you are causing the Cooling to run or open for the longer period of time needed to dehumidify the Air.

Other than Correct Design, the only way to dehumidify is to Reheat the Air, while the Cooling Valve is fully open.

One more critical piece of info, is that the Chilled Water Supply must be set at 42.0 deg F.

Sounds like your Home unit is sized incorrectly as well.

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